/*
    This file is part of the substandard lisp implementation of Standard Lisp
    Copyright (C) 2011 Nicky Nickell

    substandard lisp is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

function std_open(a, env) {
  var file = a[0].value;
  var how = a[1];
  
  var mode = CHANNEL_OUTPUT;

  if (how.value == 'output') {
    env.files[file] = '';
  }

  if (how.value == 'output') {
    mode = CHANNEL_OUTPUT;
  } else if (how.value == 'input') {
    mode = CHANNEL_INPUT;
  }

  if (env.files[file] != undefined) {
    return channel = new lisp_channel(env.files[file].slice(0), mode, file);
  } else {
    throw new lisp_error(ERROR_INTERNAL, T, "file not found")
  }
}

/*---
name: open
arity: 2
rest: false
ftype: FTYPE_EXPR

argument-types:
  - TYPE_STRING
  - TYPE_ID

doc: |
  explaining what open is / how it is used!

tests: |

...*/
